1. Field of the Invention
This invention relates to measuring devices in heart catheter laboratories and more particularly, to a pressure transducer elevation gauge which is used in heart catheterization laboratories to determine the precise vertical elevation of physiological pressure transducers to monitor hemodynamics, particularly relating to the heart. In a preferred embodiment, the pressure transducer elevation gauge is characterized by a vertical stand or support and a horizontal indicator adjustably attached to the support for precisely locating the elevation, or mid-axiallary line of the patient's heart while the patient is reclining. When the heart elevation, or heart mid-axiallary line is accurately determined by manipulation of the pressure transducer elevation gauge, the gauge is then moved to the foot of the bed and the physiologic pressure transducer is adjusted vertically on a corresponding support or stand to place the physiologic pressure transducer on the mid-axiallary line elevation of the patient's heart. The heart hemodynamics can then be monitored by operation of the physiologic pressure transducer in conventional fashion, with the assurance that the physiologic pressure transducer is operating at the precise mid-axiallary elevation of the patient's heart, to minimize error.
In the heart catheterization laboratories and intensive care units of hospitals and trauma units, physiologic pressure transducers are used to monitor the hemodynamics of the hearts of patients for various purposes. The accuracy of the data received from the physiologic pressure transducers depends upon the accuracy with which these devices are aligned with the mid-axiallary line of the patient's heart. Ideally, the physiologic pressure transducer should be located at the mid-axiallary line of the patient's heart to insure accurate measurement of the hemodynamics involved. Since critical pressure gradients may be measured by the physiologic pressure transducers, errors in elevation between each physiologic pressure transducer and the corresponding patient's heart may result in inaccurate medical conclusions and ineffective or erroneous treatment. Typically, the physiologic pressure transducer units must be mounted at the mid-axiallary level, that is, the level of the heart within the chest cavity, before the hemodynamic data is obtained. The pressure transducer elevation gauge of this invention is designed to first ascertain the mid-axiallary level of the heart of a reclining patient and then insure that the corresponding physiologic pressure transducer is located at this mid-axiallary level before the necessary hemodynamics are obtained.
2. Description of the Prior Art
Specific measurements for levelling physiologic pressure transducers in heart catheter laboratories, intensive care units and other patient care facilities in order to determine heart hemodynamics by operation of physiologic pressure transducers have been made in a variety of ways. One technique is to use a measuring stick, rod or staff and approximately determine the mid-axiallary level of the patient's heart and then locate the physiologic pressure transducer at this level near the foot of the bed. Other techniques include "guesstimating" this height by visual observation and other approximations preparatory to recording the desired hemodynamics.
Various patents are known in the art for determining the height of objects: U.S. Pat. No. 325,134 dated Aug. 25, 1885, entitled "Height Measure for Horses" to I. Wainwright; U.S. Pat. No. 2,930,133, dated Mar. 29, 1960, to J. C. Thompson, entitled "Apparatus To Aid In Determining Abnormal Positions of Spinal Vertebrae"; U.S. Pat. No. 3,133,355, dated May 19, 1964, to A. Gordon, entitled "Muscle Myotonometer"; U.S. Pat. No. 3,531,866, dated Oct. 6, 1970, to R. E. Lawler et al, entitled "Direct Reading Technique Caliper for X-Ray Machines"; U.S. Pat. No. 4,846,173, dated Jul. 11, 1989, to T. W. Davidson, entitled "Anterior Lateral Off-Axis Bite Block System for Radiation Therapy"; and U.S. Pat. No. 4,928,398, dated May 29, 1990, to Michael Delfiner, entitled "Anthropometer".